Crosslinked or thermoset polymers of strained ring polycyclic cycloolefins are relatively new materials which show great commercial promise as structural or engineering plastics. Preparation of these polymers, usually based on dicyclopentadiene, is taught, e.g., by Klosiewicz in U.S. Pat. No. 4,400,340. Klosiewicz teaches a reaction injection molding (RIM) technique wherein a first monomer stream containing a catalyst and a second monomer stream containing a catalyst activator are brought together in a mix head and substantially immediately injected into a mold where the monomer polymerizes within seconds to form a shaped article matching the shape of the mold.
In the presence of both the catalyst and the catalyst activator, polymerization is almost instantaneous. Klosiewicz teaches that a reaction rate moderator is included in the activator stream to delay the onset of polymerization for the few seconds required to transfer the reaction mass from the mix head to the mold. Other investigators have found activators that delay polymerization for as long as several minutes or, at room temperature, up to an hour or more. These activators permit the use of these reaction streams in techniques where mold filling is necessarily slow, such as in rotational molding, resin transfer molding, and RIM processes where very large structures are to be molded.
Neat polymers based on dicyclopentadiene or other strained ring polycyclic cycloolefins provide an excellent balance of stiffness and impact properties. For many applications, however, particularly for high performance structural applications such as automobile seat supports and body frames, even higher stiffness and strength are desired. For these applications, fiber reinforcement of the structure is desirable, and it has been taught, e.g., by Leach in U.S. Pat. No. 4,708,969 to form glass, graphite, or aramid fiber-reinforced structures based on cyclic olefins.
Fiber reinforced polymer structures, per se, are well known in the structural polymer art. Such materials, frequently referred to as composite materials or, more simply, composites, are widely employed, e.g., in aerospace applications and in the automobile industry.